pngplayground

Tool for experimenting with and repairing PNG files.

Designed for fixing up intentionally-broken PNGs in things like CTF events, but
hopefully useful in other scenarios too.

Features:

• Parses and interprets PNG chunks, giving you the info in plain text.
• Checks CRCs on chunks and lets you see any that are bad and optionally fix
  them automatically.
• Validates data in chunks against PNG standard and reports any errors.
• Allows extracting specific blocks to separate files for easier analysis (and
  in the future, importing specific blocks back from these files)
• Gives ability to edit all data in chunks, and optionally fix the checksums
  after.